#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>

int main() {
    int n;
    int i = 0;
    double sum = 0;
    scanf("%d", &n);
    for (i = 1; i <= n; i++)
    {
        sum += 1.0 / i;
    }
    printf("%lf", sum);
    return 0;
}